Random NSNumber from array

开发者_如何学JAVAI'm trying to make an IBAction pick a random float from an NSMutableArray (10.00, 2.56, 4.25, 1.95).

Here's what I tried:

In the viewDidLoad:

NSMutableArray *numberPicker = [NSArray arrayWithObjects:
                                  [NSNumber numberWithFloat:10.00],
                                  [NSNumber numberWithFloat:2.56],
                                  [NSNumber numberWithFloat:4.25],
                                  [NSNumber numberWithFloat:1.95],
                                  nil];

In the IBAction:

-(IBAction)buttonPressed: (id)sender{
result = [numberPicker objectAtIndex:arc4random() % [numberPicker count])];

Obviously this isn't working, i get an error "Assigning to 'float' from incompatible type 'id'". Any ideas how to get one of the numbers into "result"?

You just change one line to:

result = [[numberPicker objectAtIndex:arc4random() % [numberPicker count])] floatValue];

You could write a method randomElement in a category on NSArray

#import "NSArray+RandomUtils.h"

@implementation NSArray (RandomUtils)


-(id)randomElement
{
    if ([self count] < 1) return nil;
    NSUInteger randomIndex = arc4random() % [self count];
    return [self objectAtIndex:randomIndex];
}
@end

or just use the one, I wrote.

You will use it like this:

• #import "NSArray+RandomUtils.h"

• Use a property numberPicker @property (retain) NSArray *numberPicker

• viewDidLoad:

  self.numberPicker = [NSArray arrayWithObjects:
                            [NSNumber numberWithFloat:10.00],
                            [NSNumber numberWithFloat:2.56],
                            [NSNumber numberWithFloat:4.25],
                            [NSNumber numberWithFloat:1.95],
                            nil];
  

• in your buttonPressed: use

  result = [(NSNumber *)[self.numberPicker randomElement] floatValue];